infra/docs: Docker Hub release pipeline, versioning, README overhaul

Reference prebuilt temetro/temetro-{backend,frontend} images in docker-compose
(with a build fallback) and stop baking the frontend API URL. Add a
tag-triggered GitHub Actions release workflow that pushes both images and cuts
a GitHub Release, plus RELEASING.md, CHANGELOG.md, and a root version. Overhaul
the root and frontend READMEs (screenshot, features, prebuilt-image quickstart,
LAN access, updating).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CHANGELOG.md

@@ -0,0 +1,32 @@
+# Changelog
+
+All notable changes to temetro are recorded here. The format is loosely based on
+[Keep a Changelog](https://keepachangelog.com/), and the project follows
+[Semantic Versioning](https://semver.org/). See [RELEASING.md](./RELEASING.md)
+for how releases are cut and published.
+
+## [Unreleased]
+
+### Added
+- **Version & update awareness.** `GET /api/version` reports the running version
+  and checks GitHub Releases for a newer one; Settings → **About & updates** shows
+  the current/latest version, and an optional, dismissible banner appears when an
+  update is available.
+- **LAN access.** The frontend now resolves the backend URL from the host the
+  browser is using, so other departments can reach temetro at
+  `http://<server-LAN-IP>:3000` with no rebuild. A Settings panel surfaces the
+  shareable network address. `GET /api/network` reports detected LAN addresses.
+- **Prebuilt Docker images** published to Docker Hub (`temetro/temetro-backend`,
+  `temetro/temetro-frontend`) via a tag-triggered GitHub Actions release workflow.
+- **Voice dictation** on the AI chat input (Web Speech API), with graceful
+  fallback where the browser doesn't support it.
+
+### Changed
+- `docker-compose.yml` references the published images (with a build fallback) and
+  no longer bakes a fixed API URL into the frontend.
+
+## [0.1.0] — 2026-06-26
+
+Initial baseline: clinician AI-chat UI wired to the TypeScript/Express/Postgres
+API (Better Auth, multi-tenant clinics, org-scoped patient records), the patient
+wallet encrypted-share flow, and Dockerised local run.